Brother Mine
by SHERlockedFangirl
Summary: In facing a new, high-profile case, Lestrade calls upon Sherlock and John's combined efforts to help his team solve it as quickly as possible. But with the case comes a new Detective Sergeant, who seems oddly familiar, and appears to have a deep, burning hatred of Sherlock Holmes
1. Chapter 1

It began like many of their adventures, with a request from Lestrade to get to Scotland Yard as soon as possible.

It was 1 am when the call had come through. John had been sat in the living room typing up the latest case note to post on his blog. Sherlock stood at the window, lightly skimming the bow over the strings of his beloved violin, not playing anything in particular, but still the notes seemed to work and flow together well, like a lullaby or a nursery rhyme, composing subconsciously as he explored his mind palace.

The evening in baker Street was filled with a relaxed haze that often settled over them during the lull between cases. John had learned to enjoy these nights whilst he could, because at any given moment a client could turn up or they could get a phone call from and exhausted sounding Lestrade requesting their presence.

Which is, of course, exactly what happened.

They arrived at New Scotland Yard after a short drive through the light London traffic. There were few people still awake at this hour, which made the journey quick and painless.

Sherlock waltzed into the building as if he owned the place, which Sherlock probably thought. John sniggered at his internal commentary, quickening his steps to keep up with the long strides of the aloof Consulting Detective.

They made their way to Lestrade's office with little hassle, the officers working obviously preoccupied with the case at hand rather than insulting Sherlock. Although, John noticed, there seemed to be rather more officers than usual working at this late hour.

Lestrade was at his desk, Sally Donovan leaning over his shoulder as they sorted through a seemingly endless pile of papers and reports that were laid out before them.

"Lestrade," Sherlock greeted cordially as they entered the room.

The Detective Inspector raised his head, and sighed in obvious relief at the sight of the two of them. Sally followed her boss's gaze and sent a withering look at them, clearly she had not wanted to call them in on the case, but they were out of their depth and desperate.

_As always_, John could practically hear Sherlock's thoughts.

"Details," Sherlock demanded. John made a mental note to work on Sherlock's manners.

"Kidnapping, the only daughter of one of the higher-ups in the politics game," Lestrade began, still passing papers over his shoulder to Donovan as he continued, "10 years old. Was taken this afternoon after school. Usually attends piano lessons for an hour and a half before her parents pick her up. Never showed up to the lesson. Very out of character according to the parents and teachers. Obviously as this is a high-profile case we want to get it solved as soon as possible, hence why we've called in the extra staff."

"Any ransom demands?"

Lestrade ran his hand through his silver hair, obviously stress was high and tensions were mounting.

"Not yet."

"CCTV footage?"

"We've got officers working on that now."

Sherlock clapped his hands together, steepling his fingers as if in prayer and tucking them beneath his chin as her whirled in a circle, coat floating out gracefully behind him.

_Now he's just showing off, t_hough John.

"I need all relevant information, and now," ordered Sherlock, turning back to look at Lestrade.

Greg rose from his desk and made his way over to his two friends and sometimes-colleagues, leaving Donovan at the desk.

"We've a new Sergeant on the team who should be assembling all information regarding the case now," stated Lestrade, opening the door and holding it for John and Sherlock.

"And they're competent?" Sherlock asked as they moved into the corridor outside. "If they're anything like your current team I shouldn't have too much hope."

"Trust me, she's good. I can see her working her way through the ranks very quickly."

"Take us to her, I need to see the information."

John looked back into the room and saw Donovan with a look of resentment upon her face. She opened her mouth as if to protest, but at that precise moment, Greg shut the door, and proceeded to march them along the corridor and away from Sally Donovan's fury.

Dare he say it, John thought Donovan might be jealous of the new Sergeant. After all, she had worked for the Yard for many years, putting in God knows how many hours and working hard. It must be difficult to hear Greg talk about someone so highly, despite only being there as short while when she's been working hard for years without any mention of a promotion.

John made another mental note to show Donovan more respect.

But only if she showed more to Sherlock. After all, he couldn't respect someone who was rude and downright spiteful to his best friend.

They only walked a short distance down the corridor before Greg pulled open another door and ushered both he and Sherlock though it into another room.

The walls were covered form ceiling to floor in paper, evidence. It reminded John of their own evidence wall back in Baker Street. No smiley faces or bullet holes adorned these walls however, just photographs, reports, statements etc.

A woman - _the new Sergeant_, John assumed - was stood with her back to them when they entered the room.

From what John could see she was tall, although that was probably due to the almost inappropriate, but just the right side of professional heeled shoes she was wearing. Jet black hair, with a touch of mahogany lay elegantly on her shoulders in a style that was just too long to be called a bob, in large, luxurious waves.

She stood with her hands on her hips, accentuating their size in proportion to her petite waist, showing her flawless hourglass figure. Her hips were angled to the right, jutting out from her torso and her long, slim legs that really should be illegal to be shown in such a slim fitted pair of black work trousers. Her head was angled slightly, obviously deep in thought about the evidence that was displayed before her.

"Sherlock, John, meet Sergeant Annalese Carter. Carter, this is Sherlock Holmes and his colleague, Doctor Watson."

Her whole body tensed up at the mention of their names.

Carter turned to face them.

As she turned, her hair rustled ever so gently, and it looked like water shimmering in a gentle stream on a spring afternoon. Everything about this woman seemed to scream elegant and professional

From the front, John could see that she had been drumming her fingers along her hip bones where her hands had been resting, which were now drawn up and folded across her chest and in amongst the folds of arms and fabric, John could make out the sparkle of a large engagement ring and matching wedding band.

Her face was absolutely breath-taking, and oddly familiar. Sharp cheekbones that could cut diamonds, full lips, pale skin and glittering, pale blue eyes.

But what surprised John the most was the look of pure, open hatred in her eyes as she glared directly at Sherlock, lips setting into a thin line and eyes never blinking.

The air in the room immediately felt icy, and the tension was almost too painful to bear. A quick glance at Lestrade confirmed that John was not the only one made uncomfortable by the hostility displayed by Sergeant Carter.

Sherlock seemed to be the only one unaffected by this, his expression remained the cool mask of indifference that he seemed to adopt in these situations. And – unless John was very much mistaken, which he often wasn't in regards to Sherlock – he thought he could see a hint of a smile playing around the corners of his mouth.

John could practically hear the cogs whirring in Sherlock's brain as he regarded Sergeant Carter, and he longed to hear what deductions Sherlock had made about this woman that made him smirk like that.

And just as John was sure Sherlock was about to unleash his deductions upon her, Sherlock said something rather unexpected.

"It's been far too long, Annalese."

She stalked over to him and slapped him.


	2. Chapter 2

John and Greg had been stunned into silence.

No-one, not even Donovan, had ever shown this much contempt for Sherlock so quickly – at least not to John's knowledge.

Sherlock brought a hand up to his face to sooth the angry, red skin in the visible form of a hand on his cheek. That had to have hurt, John could practically feel the sting from the slap through the tense atmosphere that had suddenly settled on the room.

The silence continued until…

"You absolute bastard."

"Carter," Lestrade warned.

"It's perfectly alright Lestrade." Sherlock's eyes never left Sergeant Carter's. "I'm under no delusions that I am underserving of this treatment."

John snapped his head around to stare at Sherlock. Never had the man admitted to ever being at fault, let alone deserving of such hostile behaviour.

"You deserve much more than a slap to the face after what you did." Eyes of pure ice shot death glares across the room to the Consulting Detective.

"Sergeant Carter, I'm warning you," started Greg, moving between her and Sherlock, creating a physical barrier. John took a step towards Sherlock, ready to pull him from the room if Carter became more aggravated, which, in all honestly, was very probable.

"You don't understand, Greg. You have no idea, I- I can't-" John could see her struggling to restrain herself, and it was obviously a losing battle.

"Sherlock," he murmured, Sherlock turning his attention to John for the first time since they entered the room, "maybe we should leave."

"Unnecessary, John, we have a case to solve," Sherlock turned back to the wall of evidence, sidestepping Sergeant Carter to get closer to it.

"No," she began to take a step towards Sherlock, a dangerous look in her eye that caused Greg to quickly grab hold of her upper arm, gently enough not to leave a mark or be considered aggressive, but hard enough that the warning in the action was conveyed with utter clarity. "I have a case to solve." She shrugged her arm from Greg's grasp and turned to glare at him. "Greg, I refuse to work with him. I absolutely refuse."

Lestrade's expression hardened, a look of fierce determination on his features as he shook his head.

"That's not up to you, Carter."

"I'm the best chance of solving this case, Annalese and you know it." Sherlock threw his comments over his shoulder, never taking his gaze from the evidence wall, eyes dancing over all the paper and photographs attached to the usually bare, grey wall.

"No! I refuse-"

"Enough," Lestrade's voice boomed through the rather small room, the authority in his voice so plain that it nearly made John want to cower and obey his instructions. Nearly. John had been a soldier after all, and it was very hard to intimidate him. Sherlock and Sergeant Carter were another story. Carter completely froze, dropping her gaze to the floor, a slight blush grazing her pale, sharp cheeks. Sherlock had turned his attention back to the other people in the room, eyes widening ever so slightly at the tone of Lestrade's voice, the only giveaway that he was at all surprised. "Now," he began looking between the two of them, John taking a step back to slightly behind Lestrade so there was no block in the line of fire, "you either tell me what the hell happened between you two right now or you'll both be removed from the case, effective immediately."

Both Sergeant Carter and Sherlock spoke at the same time.

"Don't be ridiculous, Lestrade," scoffed the tall, too-smart-for-his-own-good detective, a disbelieving smirk playing around the corner of his lips.

"Sir, you can't do this," protested Sergeant Carter, pleading with Greg, trying to appeal to his good side by using 'sir' instead of his name, showing her professional respect for him.

Greg, however, was having absolutely none of it.

"Now," he growled.

"Sherlock," John warned him as Sherlock went to protest again.

Sherlock sighed heavily, before turning to Lestrade and John, gesturing to Sergeant Carter as he spoke.

"John, Lestrade, allow me to introduce Annalese Carter, née Holmes, my younger sister."

If it had been quiet before, after Sergeant Carter had slapped him, it was nothing compared to the silence that descended upon the room after Sherlock dropped this bombshell.

John stood there, trying desperately to compute the information. Sherlock had never before mentioned a sister, neither had Mycroft. And suddenly, here was this figure that had come into their lives, literally out of nowhere, and Sherlock was claiming that she was his unknown sibling?

Greg was the first to recover out of the two of them.

"Your what?"

"Lestrade, you do know how I detest repetition," Sherlock scowled at the Detective Inspector.

"Sister?" John asked, just to clarify, just to make sure.

"Unfortunately yes, sneered Sergeant Carter – Annalese – "now if you'll excuse me I have something to discuss with Sergeant Donovan." She promptly pushed past the men and exited the room, leaving the three men in silence behind her.

Greg ran his hands through his silver hair, breathing out a sigh – of frustration? Of relief? Of exasperation? Possibly a mixture of all three – before collecting a few pieces of paper from the walls before shoving them into John's hands.

"I think it's best you guys take this back to Baker Street with you, just let things settle here before…Well, we'll just let things settle here, smooth over the ruffles feathers, you know?"

John nodded in agreement.

"Thanks, Greg, we'll be in touch as soon as we get anything."

Greg left them to see themselves out, probably to go and begin smoothing the feather, or however he had put it.

John grabbed Sherlock by the arm and propelled him through New Scotland Yard and onto the street. He nudged Sherlock as a prompt for him to do his magical taxi summoning trick that had all the taxi's in London stopping immediately to take them home.

The taxi ride from The Yard to Baker Street was spent in absolute silence, not that John minded; he was still trying to process the events from that afternoon.

Sherlock exited the taxi as soon as they pulled up to 221, leaving John to – once again – pay the taxi fare, before following Sherlock into the building, up the seventeen stairs and into the living room of 221B.

John gently placed the paperwork from Lestrade in a neat pile on the coffee table as Sherlock flopped rather inelegantly into his chair in a dramatic flair of long limbs and expensive suit. The silence continued as John moved into the kitchen to put the kettle on.

Tea, in John's opinion, made everything better. It was a mantra he had lived by since his early twenties, when he discovered the therapeutic process of tea making and the joys of tea drinking.

After making a cuppa for both himself and Sherlock, he made his way back into the living room, and after passing off one mug – the one full of sugar – to his flatmate, she sat down in his armchair, facing his friend.

After a few more moments of silence, Sherlock put down his tea and turned his attention to John.

"So, you've got questions."

John had to chuckle at their inside joke.

"Yeah, what was all that about then? What could you possibly have done to make her hate you that much?"

Sherlock's eyes turned downwards, refusing to meet John's gaze, almost as if he was ashamed about what he was about to say.

"She didn't know," he mumbled, so quiet that John leaned forward in his chair to hear properly.

"Didn't know what?"

Sherlock took a deep breath, collecting himself before once again meeting John's eyes.

"She didn't know my suicide was faked."

* * *

Hey guys, sorry about the wait between updates. Life seems to be getting in the way at the moment, and I feel like I'm losing the motivation to keep writing - hence why this fic probably isn't as well written as some of my others. Stay with me, I know where I want to go with this fic, but it might take me longer than usual to get me there.

All my love, Scarlett x


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